An inspection apparatus for a base substrate of a multi-layered board irradiates light to the base substrate of a multilayered board to which a protective film is attached. An image of a surface, to which the protective film is attached, is picturized by a camera, so that an acceptability of a state of a via hole is inspected on the basis of a difference between a light reflectivity of the via hole and a light reflectivity of the protective film. The protective film is colored so as to lower its light reflectivity so that the difference between the light reflectivity of the via hole and that of the protective film is clearly generated. Accordingly, on the basis of the image picturized by the camera, the size of the via hole, dusts therein and the acceptability of the via hole can be accurately inspected.